a river in the Kirghiz SSR and the Uzbek SSR; a left headstream of the Syr Darya River. It is formed by the confluence of the Karakul’dzha and Tar rivers, which rise on the slopes of the Fergana and Alai ranges. Length, 180 km. Basin area, 30, 100 sq km.

The Karadar’ia is fed by snow and glaciers. The average discharge at the point where the river leaves the mountains (140 km from its mouth) is 121 cu m per sec, with the greatest discharge occurring in June and the lowest in the winter. Its major tributaries are the Kurshab from the left and the Iassy, Kugart, and Karaunkiur from the right. Its water is used heavily for irrigation in the Fergana Valley, where the Kuigan-Iar Dam has beenbuilt on the river and where the Kardar’ia is intersected by the Bol’shoi Fergana Canal. As of 1973, the Andizhan Reservoirwas being constructed on the river. The city of Uzgen is located on the Karadar’ia.